import java.util.List;

public class MySingleList implements IList{
   static class ListNode{
       public int val;
       public ListNode next;

       public ListNode(int val) {
           this.val = val;
       }
   }
   public ListNode head;
   public void create(){
       ListNode node1=new ListNode(12);
       ListNode node2=new ListNode(23);
       ListNode node3=new ListNode(34);
       ListNode node4=new ListNode(45);
       node1.next=node2;
       node2.next=node3;
       node3.next=node4;
       head=node1;
   }
    @Override
    public void display() {
       ListNode cur=head;
         while(cur!=null){
             System.out.println(cur.val);
             cur=cur.next;
         }
        System.out.println();
    }
    @Override
    public void addFirst(int data) {
         ListNode node=new ListNode(data);
         node.next=head;
         head=node;
    }

    @Override
    public void addLast(int data) {
       ListNode  node=new ListNode(data);
       if(head==null){
           head=node;
       }
       ListNode cur=head;
       while(cur.next!=null){
           cur=cur.next;
       }
       cur.next=node;


    }

    @Override
    public void addIndex(int index, int data) {

    }

    @Override
    public boolean contains(int key) {
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {

    }

    @Override
    public void removeAllKey(int key) {

    }

    @Override
    public int size() {
        return 0;
    }

    @Override
    public void clear() {

    }


}
